If it actually goes into action, this means when phones are stolen, the thieves (or subsequent customers) won’t be able to reactivate them on any of the major networks. That ought to reduce the incentive to steal phones in the first place.

Every phone can be identified via its International Mobile Equipment Identify (IMEI) number. In some countries, the IMEI number can be used to blacklist stolen phones and render them useless. And doing this actually has reduced the incidences of mobile phone thefts.

This hasn’t been the case in the United States, and it has some ATT customers upset.

According to Forbes reporter Kashmir Hill, a class action lawsuit has been filed in California. The plaintiffs in the case — Hilary White, Jeff Pello, and Natalie Warren all had their iPhone stolen, and they think ATT could have been tracking stolen phones all along.

Hill dug through the complaint and found the reason for the lawsuit:

ATT has “[made] millions of dollars in improper profits, by forcing legitimate customers, such as these Plaintiffs, to buy new cell phones, and buy new cell phone plans, while the criminals who stole the phone are able to simply walk into ATT stories and ‘re-activate’ the devices, using different, cheap, readily-available ‘SIM’ cards.”

ATT, on the other hand, thinks that its move to join the other three carriers and FCC shows that they take the problem of smartphone thefts seriously and are doing their best to prevent those crimes.